For eighteen years Abdullah Öcalan has been imprisoned on an island in the middle of the Sea of Marmara. Once an Ottoman naval base used against the Byzantines, the island of İmralı is now a modern Château d’If, designed to hold the man successive Turkish governments have regarded as the greatest threat to “the indivisible unity of the Sublime Turkish State”. Öcalan commanded the Kurdistan Workers’ Party (PKK) during the height of its war, in the 1980s and 90s, to establish an independent Kurdistan in south-eastern Turkey. His capture in 1999 was met in western Turkey with fevered triumphalism, but Öcalan’s incarceration has done little to dampen Kurdish ambitions for political autonomy. The PKK remains in the mountains on Turkey’s periphery, attacking Turkish army outposts and harried by Turkish F-16s; over the past two years the war has reignited at a level not seen for decades, with entire…